1. Field of the Invention
The present invention relates to a motor provided with a turntable and a method for manufacturing the motor. More particularly, the present invention relates to a motor provided with a chucking device which enables attachment and detachment of a disk-shaped storage medium such as CD or DVD.
2. Description of the Related Art
Reduction in size and height of optical storage devices using disk-shaped storage media such as CDs and DVDs has been demanded in recent years. To keep up with this demand, motors provided with chucking devices each enabling attachment and detachment of an optical storage medium are required to be improved in the following two aspects. First, reduction in size and height is also required for motors with the reduction in size and height of optical storage devices into which motors are incorporated. Second, motors have to have improved impact resistance. This request occurs because optical storage devices into which motors are incorporated are often carried due to the reduction in size and height thereof. In order to satisfy the second request, it is necessary to increase securing strength between the respective components of motors. In particular, a shaft to which a load is applied during an operation of the motor, a rotor holder which holds a rotor magnet and is subjected to a driving force, and a turntable on which an optical storage medium is mounted have to be strongly secured to one other.
In accordance with conventional techniques, the shaft, the rotor holder, and the turntable are bonded to one other with adhesive. FIG. 19 illustrates an exemplary manner of bonding the rotor holder and the turntable to the shaft with adhesive.
Referring to FIG. 19, the rotor holder 360 is hollow, approximately cylindrical and has a bottom. At the center of the bottom is formed a through hole. The turntable 320, which is approximately disk-shaped, also has a through hole at its center. Hereinafter, the through hole of the rotor holder 360 and the through hole of the turntable 320 are referred to as the rotor-holder through hole and the turntable through hole, respectively, for the sake of convenience. The shaft 310 penetrates through both the through holes of the rotor holder 360 and the turntable 320. The bottom of the rotor holder 360 is in contact with the turntable 320. Adhesive is applied on an outer surface of the shaft 310, an inner circumferential surface of the rotor holder 360 which defines the rotor-holder through hole, and an inner circumferential surface of the turntable 320 which defines the turntable through hole. Also, adhesive is applied on surfaces of the rotor holder 360 and the turntable 320, which are in contact with each other. The applied adhesive is then solidified, thereby securing the shaft 310, the rotor holder 360, and the turntable 320 to one another. As described above, the rotor holder 360 and the turntable 320 to the shaft 310 are secured with adhesive to one another in accordance with the conventional technique.
When the aforementioned conventional technique is used, an area of adhesion has to be increased in order to increase the strength of securing the rotor holder and the turntable to the shaft. In order to increase the area of adhesion, it is necessary to increase the diameter or axial length of the shaft. However, both the increase in diameter of the shaft and the increase in axial length of the shaft make the reduction in size and height of the motor difficult.
That is, when the aforementioned conventional securing structure continues to be used, the recent demands for increasing the strength of securing the rotor holder and the turntable to the shaft cannot be satisfied. Thus, a novel securing structure for securing the shaft, the turntable, and the rotor holder to one another is required which satisfies both the demands for the reduction in height of the motor and the demands for increasing the securing strength.